Renault is running out of patience with Red Bull, and may not wait until July for a decision on 2019 engine supplies.
Red Bull's current deal with the manufacturer expires at the end of the season. Originally Renault said it wanted to know the team's plans in May, but Red Bull have delayed the decision until the Austrian Grand Prix.
That's not gone down well with Renault.
"We have extended the deadline due to the 12 years of good cooperation that we have had," Renault boss Cyril Abiteboul told Marca.
"In Montreal they saw our new specification and that of Honda - they have all the information. I see absolutely no reason to delay this further.
"In Austria, our offer is not going to be there anymore," he warned. "They'll have to talk to Honda."
Renault's engine technical boss Remi Taffin told France's Auto Hebdo that the tension between Renault and Red Bull - which between them successfully won four constructors titles back-to-back - was understandable.
"It's been 12 years that we work together, winning a lot of races and world championships," he said. "[But] you have to be pragmatic.
"We must not forget the 600 people in Milton Keynes, and the 400 in Viry-Chattilon. They all get on well, so we have to put that at the centre of the game."
Red Bull's junior team Toro Rosso switched to Honda power at the beginning of the season. Despite it's recent turbulent time with McLaren, the Japanese manufacturer has restored its reputation with the new partnership.
A new Honda unit supplied to the team for the Canadian Grand Prix was estimated to add an extra three tenths of s second to the performance, according to Red Bull motorsports boss Dr Helmut Marko.
That's ruffled feathers at Renault, with Taffin keen to point out that the Renault unit had made similar progress.
"The improvement since Melbourne has been three tenths, including one tenth thanks to new fuel introduced in Barcelona," he said.
"It is the equivalent of about 20hp, which is in line with our expectations.
"We are already working on the next evolution, which will take place after the summer factory shutdown."
Gallery: The beautiful wives and girlfriends of F1 drivers
Keep up to date with all the F1 news via Facebook and Twitter
